Gauge line purging system for oil cracking plants



R. M. PARSONS 2,068,696

GAUGE LINE PURGING SYSTEM FOR OIL CRACKING PLANTS Filed March 2, 1935 Jan. 26, 1937.

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mum/muggy INYENTOR 105411 film-011s Patented Jan. 26, 1937 v UNITED STATES PATENT OFFICE GAUGE LINE PURGING SYSTEM FOR OIL CRACKING PLANTS Application March 2, 1935, Serial No. 8,991

2 Claims.

This invention relates to oil refining and more particularly to an oil cracking plant having equipment operating under pressure.

An object of the invention is to provide a system of pressure gauges, operatively associated with the various pressure devices, and located at a central point, as on a control panel.

Another object is to ensure that the gauges accurately register the pressure within the devices.

Another object is to provide means to clear the gauge lines of impediments, such as coke, which would interfere with the accurate registration of the gauges.

Another object is to provide means to periodically purge or clean the gauge lines without dismantling the apparatus.

Another object is to prevent the purging means from injuring the gauges.

A further object is to provide a simple, convenient and dependable means for accomplishing the above purposes.

Various other objects will be apparent as the nature of the invention is more fully disclosed.

Although the novel features which are believed to be characteristic of this invention will be more particularly pointed out in the claims appended hereto, the invention itself, as to its objects and advantages and the manner of its organization,

will be better understood by referring to the following description taken in connection with the accompanying drawing in which one embodiment is shown for purposes of illustration.

In the drawing:

Fig. 1 is a diagrammatic representation of a typical oil cracking plant illustrating the present invention as applied thereto; and

Fig. 2 is an enlarged detail View of a two-way valve used therein.

In the following description and in the claims various parts are identified by specific names for convenience but they are to be interpreted as broadly as the art will permit.

.Referring to the drawing more in detail the 5 invention is shown as applied to a typical oil cracking plant comprising a furnace I 0 having convection tubes I I and radiant heat tubes I2, a reaction chamber I3, a flash chamber I4 and a fractionating column I5. The tubes I2 of the 50 furnace III are connected by a pipe I6 to the top of the reaction chamber I3. The lower part of said. reaction chamber is connected by a pipe I! and a pressure reduction valve I8 to an intermediate point in the flash chamber I4. The

55 top of the flash chamber I4 is connected by a pipe I9 to the fractionating column I5. Condensed liquid is withdrawn from the bottom of the fractionating column I5 through a pipe 2|] leading to a hot oil pump 2| which discharges through a pipe 22 to the tubes II of the furnace I0. Heavy liquid is removed from the flash chamber I4 by a discharge pipe 23 connected to a well 24 formed at the bottom of said chamber M. The vapors are removed from the top of the fractionating column I5 through a pipe 25 10 connected through a cooler 25 to a gasoline separator 2'I. Condensed liquid is removed from the latter by a discharge pipe 28 having a float actuated valve 29 therein to control the rate of discharge in accordance with the liquid level 1 therein. The vapors are removed from the gasoline separator 27 through a pipe 30 leading to a storage tank 3I and having a pressure reduction valve 32 and a pressure relief valve 33 associated therewith. The tank 3| discharges 20 through a pipe 34. The charging stock is applied to the fractionating column I5 through a pipe 36.

In operation, 011 for cracking is supplied to the furnace III by the hot oil pump 2| and is passed through the convection tubes II and the 25 radiant heat tubes I2 wherein it is heated to cracking temperature. The oil, at cracking temperature and at high pressure, is passed to the reaction chamber I3 wherein the vapors remain a sufficient length of time for the cracking re- 30 action to be completed. The liquid and vapor are then flashed into the flash chamber I4 at a reduced pressure so as to separate the cracked vapors from the heavy residuum which is removed from the bottom of the chamber by the pipe 23. The cracked vapor then passes to the fractionating column wherein the low boiling constituents are separated, a desired fraction such as gasoline is condensed therefrom in the cooler 26 and is collected in the gasoline sepa- 40 rator 21, and the lighter constituents are passed at reduced pressure to the storage tank 3|. The heavy condensate from the fractionating column I5 is recycled through the pipe 20 to the hot oil pump 2 I.

It is to be understood that the above system is a typical oil treating plant and only so much thereof has been set forth as is necessary to an understanding of this invention. The apparatus may be varied in details and in the manner of operation without departing from the scope of the invention.

In equipment of the above type it is desirable to maintain an accurate pressure control. For this purpose a plurality of pressure gauges are employed which are preferably located at a central point, as on a control panel, remote from the apparatus itself. In such cases the gauges are connected to the remote apparatus by small tubes which may be of considerable length.

In the example shown a plurality of gauges 40 to 43 are mounted on a panel M which may be located at some convenient point, as in the control room. The gauges 48 to 43 are connected by lines 35 to 48 respectively, consisting of small tubes adapted to transmit fluid pressure from the apparatus to the gauges, to the various devices the pressure of which is to be registered. The lines 45 to 48 are illustrated as connected respectively to the reaction chamber It, the flash chamber M, the gasoline separator 21 and the high pressure side of the hot oil pump 2|. A set of hand valves 50 to 53 may be included in the lines 35 to 48 respectively, preferably at a point near the associated apparatus, to permit the lines to be shut off in case of leakage or for repairs.

One difliculty frequently experienced in systems of the above character consists in the tendency of the small gauge lines 55 to 38 to clog, as due to coke forming or being forced therein, particularly at the point of connection to the remote apparatus. In order to ensure correct operation of the gauges it is also essential to maintain the gauge line free from moisture and vapors.

The present invention overcomes the above difficulties by the provision of means to periodically blow out or purge the gauge lines. This means is illustrated as comprising a pressure source, such as a hand pump 55, receiving a fluid, such for example as gas oil, from a storage tank 55 through a line 41 containing a check valve 58. The pump 55 discharges to a manifold 59, connected to the gauge lines l to 58 by a set of two-way valves 59 to 53 respectively, which may be conveniently located on the panel M and are adapted to connect the gauge lines either to the gauges or to the manifold. The valves 50 to 53 may, for example, be of the type shown in Fig. 2 which comprises a valve housing 65 having a plurality of ports 85, 51 and 68 adapted to be connected respectively to a gauge such as the gauge id, to a gauge line 55 and to the manifold 59. A valve member 69 having a passage interconnecting two ports, for example the ports 65 and 61 or the ports 8'! and 58, is rotatably seated in the housing 65. This passage 10 is adapted to connect the port 51 with either the port 55 or the port 68 depending upon the position of the valve member 89. A gauge H may be associated with the manifold 59 to show the pressure therein.

This gauge i! may also be mounted on the panel M. Obviously the pump 55 may be located in a position from which the various gauges and the valves 50 to 63 are easily accessible.

In the operation of the purging system, one valve, for example the valve 60, is operated todisconnect the line 45 from the gauge 40 and to connect the line 45 to the manifold 59. The pump 55 is then actuated to build up pressure in the manifold 59 and in the line 45 sufficient to purge the line of any obstructions. The pump is adapted to build up a pressure of the order of 2000 pounds per sq. in. if necessary for this purpose. The condition of the line 45 is indicated by the gauge ii. If the line is obstructed the pressure builds up until the obstruction is cleaned when the pressure drops to that of the associated apparatus, in the above example to that of the reaction chamber l3. The fluid in the manifold thus purges the entire line, removes coke, vapors or moisture and ensures the correct registration of the pressure on the gauge 40. After the line 45 has been cleaned the valve 50 is returned to its original position to again connect the line to the gauge 50 and the operation is repeated until all of the gauge lines have been cleaned. It is to be noted that the two-way valves 60 to 63 are so constructed that pressure cannot be applied to the gauge lines until the gauges have been disconnected therefrom, thereby preventing injury to the gauges by the pressure of the fluid in the manifold 59. It is obvious that should the liquid remaining inthe gauge lines solidify or otherwise clog the gauge line, it may be purged by forcing additional liquid therethrough from the pump 55 in the manner above described.

While a hand pump has been found convenient for the above system, it is obvious that other sources of pressure may be employed if desired. It is also to be understood that the system is applicable to any number or arrangement of gauge lines and is not to be restricted to the specified lines or to the specific apparatus above described. The purging system has been shown as applied to a typical oil cracking plant merely for purposes of illustration. Various changes or modifications may be made by a person skilled in the art. The invention is accordingly to be limited only in accordance with the following claims when interpreted in view of the prior art.

What is claimed is:

1. In an oil cracking plant having a reaction chamber, a flash chamber, a gasoline separator and a pump to deliver stock to a furnace for heating, a set of pressure gauges located at a central point, individual lines connecting the respective gauges to said reaction chamber, to said flash chamber, to said gasoline separator and to the high pressure side of said pump, for the transmission of fluid pressure therefrom to said gauges, a source of high fluid pressure, a manifold connecting said source to each of said lines, and a two-way valve at said central point associated with each line to selectively connect the same to said gauge for rendering the gauge operative, or to said manifold for purging purposes, said source being adapted to build up pressure in said line to purge the same whereby the correct functioning of said gauge may be assured.

2. In an oil cracking plant, in combination, a plurality of devices containing hydrocarbon fluid under pressure distributed about said plant, a central station, a plurality of pressure gauges at said central station, fluid pressure lines connecting the individual gauges to said respec tive devices for transmitting fluid pressure from said devices to said gauges, and a purging system comprising a source of high fluid pressure, a manifold connecting said source to each of said lines at a point near the gauges and a control valve in each line at said point adapted to close the passage from the manifold to each gauge and to connect the manifold to said line, whereby fluid under pressure may be passed from the manifold through said line for purging the same without injuring the gauge.

RALPH PARSONS. 

